Organic semiconductors can be used very simply and cost-effectively as active material in spectrally tunable lasers. In general, polymers and small molecules are used as organically active material. With optical excitation by means of suitable external laser sources, laser operation in the entire visible spectral range is thus possible. It has not been possible hitherto to demonstrate a direct electrical driving of organic semiconductors, on account of the low charge carrier mobility and the resultant absorption in charged semiconductor films. Hitherto the laser excitation has always been effected by means of expensive external laser sources that take up a large amount of space.